CVE-2021-3733

NameCVE-2021-3733
DescriptionThere's a flaw in urllib's AbstractBasicAuthHandler class. An attacker who controls a malicious HTTP server that an HTTP client (such as web browser) connects to, could trigger a Regular Expression Denial of Service (ReDOS) during an authentication request with a specially crafted payload that is sent by the server to the client. The greatest threat that this flaw poses is to application availability.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2808-1, DLA-3432-1, DLA-3477-1, ELA-510-1, ELA-853-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
python2.7 (PTS)jessie, jessie (lts)2.7.9-2-ds1-1+deb8u11fixed
stretch (security)2.7.13-2+deb9u6vulnerable
stretch (lts), stretch2.7.13-2+deb9u8fixed
buster2.7.16-2+deb10u1vulnerable
buster (security)2.7.16-2+deb10u3fixed
bullseye2.7.18-8vulnerable
python3.4 (PTS)jessie, jessie (lts)3.4.2-1+deb8u15fixed
python3.5 (PTS)stretch (security)3.5.3-1+deb9u5fixed
stretch (lts), stretch3.5.3-1+deb9u7fixed
python3.7 (PTS)buster3.7.3-2+deb10u3vulnerable
buster (security)3.7.3-2+deb10u5fixed
python3.9 (PTS)bullseye3.9.2-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
python2.7sourcejessie2.7.9-2-ds1-1+deb8u10ELA-853-1
python2.7sourcestretch2.7.13-2+deb9u7ELA-853-1
python2.7sourcebuster2.7.16-2+deb10u2DLA-3432-1
python2.7source(unstable)(unfixed)
python3.4sourcejessie3.4.2-1+deb8u11ELA-510-1
python3.5sourcestretch3.5.3-1+deb9u5DLA-2808-1
python3.5source(unstable)(unfixed)
python3.7sourcebuster3.7.3-2+deb10u5DLA-3477-1
python3.7source(unstable)(unfixed)
python3.9source(unstable)3.9.7-1

Notes

[bullseye] - python3.9 <no-dsa> (Minor issue)
[bullseye] - python2.7 <ignored> (Unsupported in Bullseye, only included to build a few applications)
https://bugs.python.org/issue43075
https://github.com/python/cpython/pull/24391
https://github.com/python/cpython/commit/7215d1ae25525c92b026166f9d5cac85fb1defe1 (master)
https://github.com/python/cpython/commit/a21d4fbd549ec9685068a113660553d7f80d9b09 (3.9.5)
https://github.com/python/cpython/commit/e7654b6046090914a8323931ed759a94a5f85d60 (3.8.10)
https://github.com/python/cpython/commit/ada14995870abddc277addf57dd690a2af04c2da (3.7.11)
https://github.com/python/cpython/commit/3fbe96123aeb66664fa547a8f6022efa2dc8788f (3.6.14)

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